Here is a Halo Combat Evolved trick. It is well-known, but it's very funny. When you are playing mission 10, which is the last mission, on the part with the warthog run, you can hear a funny grunt statement. On the long S shaped tunnels, there are shortcuts. On the last of the 3 S curves, Inside the shortcut is a tunnel. If you go in it you will see a grunt at the end. Walk up to him to hear something hilarious.